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410c8acf | 1 | /* -*-c-*- |
410c8acf | 2 | * |
3 | * Key exchange protocol | |
4 | * | |
5 | * (c) 2001 Straylight/Edgeware | |
6 | */ | |
7 | ||
e04c2d50 | 8 | /*----- Licensing notice --------------------------------------------------* |
410c8acf | 9 | * |
10 | * This file is part of Trivial IP Encryption (TrIPE). | |
11 | * | |
12 | * TrIPE is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
e04c2d50 | 16 | * |
410c8acf | 17 | * TrIPE is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
e04c2d50 | 21 | * |
410c8acf | 22 | * You should have received a copy of the GNU General Public License |
23 | * along with TrIPE; if not, write to the Free Software Foundation, | |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | */ | |
26 | ||
410c8acf | 27 | /*----- Header files ------------------------------------------------------*/ |
28 | ||
29 | #include "tripe.h" | |
30 | ||
737cc271 | 31 | /*----- Brief protocol overview -------------------------------------------* |
32 | * | |
33 | * Let %$G$% be a cyclic group; let %$g$% be a generator of %$G$%, and let | |
34 | * %$q$% be the order of %$G$%; for a key %$K$%, let %$E_K(\cdot)$% denote | |
35 | * application of the symmetric packet protocol to a message; let | |
36 | * %$H(\cdot)$% be the random oracle. Let $\alpha \inr \{0,\ldots,q - 1\}$% | |
37 | * be Alice's private key; let %$a = g^\alpha$% be her public key; let %$b$% | |
38 | * be Bob's public key. | |
39 | * | |
40 | * At the beginning of the session, Alice chooses | |
41 | * | |
42 | * %$\rho_A \inr \{0, \ldots q - 1\}$% | |
43 | * | |
44 | * We also have: | |
45 | * | |
46 | * %$r_A = g^{\rho_A}$% Alice's challenge | |
47 | * %$c_A = H(\cookie{cookie}, r_A)$% Alice's cookie | |
9317aa92 | 48 | * %$v_A = \rho_A \xor H(\cookie{expected-reply}, a, r_A, r_B, b^{\rho_A})$% |
e04c2d50 | 49 | * Alice's challenge check value |
737cc271 | 50 | * %$r_B^\alpha = a^{\rho_B}$% Alice's reply |
51 | * %$K = r_B^{\rho_A} = r_B^{\rho_A} = g^{\rho_A\rho_B}$% | |
e04c2d50 | 52 | * Alice and Bob's shared secret key |
737cc271 | 53 | * %$w_A = H(\cookie{switch-request}, c_A, c_B)$% |
e04c2d50 | 54 | * Alice's switch request value |
737cc271 | 55 | * %$u_A = H(\cookie{switch-confirm}, c_A, c_B)$% |
e04c2d50 | 56 | * Alice's switch confirm value |
737cc271 | 57 | * |
58 | * The messages are then: | |
59 | * | |
60 | * %$\cookie{kx-pre-challenge}, r_A$% | |
61 | * Initial greeting. In state @KXS_CHAL@. | |
62 | * | |
737cc271 | 63 | * %$\cookie{kx-challenge}, r_A, c_B, v_A$% |
64 | * Here's a full challenge for you to answer. | |
65 | * | |
28461f0e | 66 | * %$\cookie{kx-reply}, r_A, c_B, v_A, E_K(r_B^\alpha))$% |
737cc271 | 67 | * Challenge accpeted: here's the answer. Commit to my challenge. Move |
68 | * to @KXS_COMMIT@. | |
69 | * | |
3cdc3f3a | 70 | * %$\cookie{kx-switch-rq}, c_A, c_B, E_K(r_B^\alpha, w_A))$% |
737cc271 | 71 | * Reply received: here's my reply. Committed; send data; move to |
72 | * @KXS_SWITCH@. | |
73 | * | |
74 | * %$\cookie{kx-switch-ok}, E_K(u_A))$% | |
75 | * Switch received. Committed; send data; move to @KXS_SWITCH@. | |
e04c2d50 | 76 | */ |
737cc271 | 77 | |
3cdc3f3a | 78 | /*----- Static tables -----------------------------------------------------*/ |
79 | ||
80 | static const char *const pkname[] = { | |
c3c51798 | 81 | "pre-challenge", "challenge", "reply", "switch-rq", "switch-ok" |
3cdc3f3a | 82 | }; |
0617b6e7 | 83 | |
84 | /*----- Various utilities -------------------------------------------------*/ | |
410c8acf | 85 | |
e9fac70c MW |
86 | /* --- @VALIDP@ --- * |
87 | * | |
88 | * Arguments: @const keyexch *kx@ = key exchange state | |
89 | * @time_t now@ = current time in seconds | |
90 | * | |
91 | * Returns: Whether the challenge in the key-exchange state is still | |
92 | * valid or should be regenerated. | |
93 | */ | |
94 | ||
95 | #define VALIDP(kx, now) ((now) < (kx)->t_valid) | |
96 | ||
52c03a2a | 97 | /* --- @hashge@ --- * |
410c8acf | 98 | * |
b5c45da1 | 99 | * Arguments: @ghash *h@ = pointer to hash context |
5b9f3d37 MW |
100 | * @const dhgrp *g@ = pointer to group |
101 | * @const dhge *Y@ = pointer to group element | |
410c8acf | 102 | * |
103 | * Returns: --- | |
104 | * | |
52c03a2a | 105 | * Use: Adds the hash of a group element to the context. Corrupts |
106 | * @buf_t@. | |
410c8acf | 107 | */ |
108 | ||
5b9f3d37 | 109 | static void hashge(ghash *h, const dhgrp *g, const dhge *Y) |
410c8acf | 110 | { |
111 | buf b; | |
35c8b547 | 112 | |
0617b6e7 | 113 | buf_init(&b, buf_t, sizeof(buf_t)); |
5b9f3d37 | 114 | g->ops->stge(g, &b, Y, DHFMT_HASH); |
410c8acf | 115 | assert(BOK(&b)); |
b5c45da1 | 116 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
410c8acf | 117 | } |
118 | ||
de7bd20b | 119 | /* --- @mpmask@ --- * |
5d418e24 | 120 | * |
de7bd20b | 121 | * Arguments: @buf *b@ = output buffer |
5b9f3d37 MW |
122 | * @const dhgrp *g@ = the group |
123 | * @const dhsc *x@ = the plaintext scalar | |
de7bd20b | 124 | * @size_t n@ = the expected size of the plaintext |
35c8b547 | 125 | * @gcipher *mgfc@ = mask-generating function to use |
5d418e24 | 126 | * @const octet *k@ = pointer to key material |
de7bd20b | 127 | * @size_t ksz@ = size of the key |
5d418e24 | 128 | * |
c13541b1 | 129 | * Returns: --- |
5d418e24 | 130 | * |
5b9f3d37 MW |
131 | * Use: Masks a scalar: returns %$x \xor H(k)$%, so it's a random |
132 | * oracle thing rather than an encryption thing. Breaks the | |
133 | * output buffer on error. | |
5d418e24 | 134 | */ |
135 | ||
5b9f3d37 | 136 | static void mpmask(buf *b, const dhgrp *g, const dhsc *x, size_t n, |
c13541b1 | 137 | const gccipher *mgfc, const octet *k, size_t ksz) |
5d418e24 | 138 | { |
b5c45da1 | 139 | gcipher *mgf; |
de7bd20b | 140 | octet *p; |
5d418e24 | 141 | |
c13541b1 | 142 | if ((p = buf_get(b, n)) == 0) return; |
35c8b547 | 143 | mgf = GC_INIT(mgfc, k, ksz); |
de7bd20b | 144 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
5b9f3d37 | 145 | trace(T_CRYPTO, "crypto: masking scalar = %s", g->ops->scstr(g, x)); |
61682d34 | 146 | trace_block(T_CRYPTO, "crypto: masking key", k, ksz); |
de7bd20b | 147 | })) |
5b9f3d37 | 148 | if (g->ops->stsc(g, buf_t, n, x)) { buf_break(b); return; } |
de7bd20b MW |
149 | GC_ENCRYPT(mgf, buf_t, p, n); |
150 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
5b9f3d37 | 151 | trace_block(T_CRYPTO, "crypto: scalar plaintext", buf_t, n); |
61682d34 | 152 | trace_block(T_CRYPTO, "crypto: masked ciphertext", p, n); |
de7bd20b | 153 | })) |
b5c45da1 | 154 | GC_DESTROY(mgf); |
b5c45da1 | 155 | } |
156 | ||
de7bd20b MW |
157 | /* --- @mpunmask@ --- * |
158 | * | |
5b9f3d37 | 159 | * Arguments: @const dhgrp *g@ = the group |
de7bd20b MW |
160 | * @const octet *p@ = pointer to the ciphertext |
161 | * @size_t n@ = the size of the ciphertext | |
35c8b547 | 162 | * @gcipher *mgfc@ = mask-generating function to use |
de7bd20b MW |
163 | * @const octet *k@ = pointer to key material |
164 | * @size_t ksz@ = size of the key | |
165 | * | |
5b9f3d37 | 166 | * Returns: The decrypted scalar, or null. |
de7bd20b | 167 | * |
5b9f3d37 | 168 | * Use: Unmasks a scalar. |
de7bd20b MW |
169 | */ |
170 | ||
5b9f3d37 | 171 | static dhsc *mpunmask(const dhgrp *g, const octet *p, size_t n, |
76e91db9 | 172 | const gccipher *mgfc, const octet *k, size_t ksz) |
b5c45da1 | 173 | { |
174 | gcipher *mgf; | |
5b9f3d37 | 175 | dhsc *x; |
b5c45da1 | 176 | |
35c8b547 | 177 | mgf = GC_INIT(mgfc, k, ksz); |
de7bd20b | 178 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
61682d34 MW |
179 | trace_block(T_CRYPTO, "crypto: unmasking key", k, ksz); |
180 | trace_block(T_CRYPTO, "crypto: masked ciphertext", p, n); | |
de7bd20b MW |
181 | })) |
182 | GC_DECRYPT(mgf, p, buf_t, n); | |
5b9f3d37 | 183 | x = g->ops->ldsc(g, buf_t, n); |
de7bd20b | 184 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
5b9f3d37 MW |
185 | trace_block(T_CRYPTO, "crypto: scalar plaintext", buf_t, n); |
186 | trace(T_CRYPTO, "crypto: unmasked scalar = %s", | |
187 | x ? g->ops->scstr(g, x) : "<failed>"); | |
de7bd20b | 188 | })) |
b5c45da1 | 189 | GC_DESTROY(mgf); |
5b9f3d37 | 190 | return (x); |
de7bd20b MW |
191 | } |
192 | ||
193 | /* --- @hashcheck@ --- * | |
194 | * | |
35c8b547 | 195 | * Arguments: @keyexch *kx@ = pointer to key-exchange block |
5b9f3d37 MW |
196 | * @const dhge *K@ = sender's public key |
197 | * @const dhge *CC@ = receiver's challenge | |
198 | * @const dhge *C@ = sender's challenge | |
199 | * @const dhge *Y@ = reply to sender's challenge | |
de7bd20b MW |
200 | * |
201 | * Returns: Pointer to the hash value (in @buf_t@) | |
202 | * | |
203 | * Use: Computes the check-value hash, used to mask or unmask | |
204 | * indices to prove the validity of challenges. This computes | |
205 | * the masking key used in challenge check values. This is | |
206 | * really the heart of the whole thing, since it ensures that | |
5b9f3d37 | 207 | * the scalar can be recovered from the history of hashing |
de7bd20b MW |
208 | * queries, which gives us (a) a proof that the authentication |
209 | * process is zero-knowledge, and (b) a proof that the whole | |
210 | * key-exchange is deniable. | |
211 | */ | |
212 | ||
5b9f3d37 MW |
213 | static const octet *hashcheck(keyexch *kx, const dhge *K, |
214 | const dhge *CC, const dhge *C, const dhge *Y) | |
de7bd20b | 215 | { |
35c8b547 | 216 | ghash *h = GH_INIT(kx->kpriv->algs.h); |
5b9f3d37 | 217 | const dhgrp *g = kx->kpriv->grp; |
de7bd20b MW |
218 | |
219 | HASH_STRING(h, "tripe-expected-reply"); | |
5b9f3d37 MW |
220 | hashge(h, g, K); |
221 | hashge(h, g, CC); | |
222 | hashge(h, g, C); | |
223 | hashge(h, g, Y); | |
de7bd20b MW |
224 | GH_DONE(h, buf_t); |
225 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
61682d34 | 226 | trace(T_CRYPTO, "crypto: computing challenge check hash"); |
5b9f3d37 MW |
227 | trace(T_CRYPTO, "crypto: public key = %s", g->ops->gestr(g, K)); |
228 | trace(T_CRYPTO, "crypto: receiver challenge = %s", g->ops->gestr(g, CC)); | |
229 | trace(T_CRYPTO, "crypto: sender challenge = %s", g->ops->gestr(g, C)); | |
230 | trace(T_CRYPTO, "crypto: sender reply = %s", g->ops->gestr(g, Y)); | |
35c8b547 | 231 | trace_block(T_CRYPTO, "crypto: hash output", buf_t, kx->kpriv->algs.hashsz); |
de7bd20b MW |
232 | })) |
233 | GH_DESTROY(h); | |
234 | return (buf_t); | |
235 | } | |
236 | ||
237 | /* --- @sendchallenge@ --- * | |
238 | * | |
239 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
240 | * @buf *b@ = output buffer for challenge | |
5b9f3d37 | 241 | * @const dhge *C@ = peer's actual challenge |
de7bd20b MW |
242 | * @const octet *hc@ = peer's challenge cookie |
243 | * | |
244 | * Returns: --- | |
245 | * | |
246 | * Use: Writes a full challenge to the message buffer. | |
247 | */ | |
248 | ||
5b9f3d37 MW |
249 | static void sendchallenge(keyexch *kx, buf *b, |
250 | const dhge *C, const octet *hc) | |
de7bd20b | 251 | { |
5b9f3d37 MW |
252 | const dhgrp *g = kx->kpriv->grp; |
253 | g->ops->stge(g, b, kx->C, DHFMT_VAR); | |
35c8b547 | 254 | buf_put(b, hc, kx->kpriv->algs.hashsz); |
5b9f3d37 MW |
255 | mpmask(b, g, kx->a, g->scsz, kx->kpriv->algs.mgf, |
256 | hashcheck(kx, kx->kpriv->K, C, kx->C, kx->RX), | |
35c8b547 | 257 | kx->kpriv->algs.hashsz); |
5d418e24 | 258 | } |
259 | ||
410c8acf | 260 | /* --- @timer@ --- * |
261 | * | |
262 | * Arguments: @struct timeval *tv@ = the current time | |
263 | * @void *v@ = pointer to key exchange context | |
264 | * | |
265 | * Returns: --- | |
266 | * | |
267 | * Use: Acts when the key exchange timer goes off. | |
268 | */ | |
269 | ||
270 | static void timer(struct timeval *tv, void *v) | |
271 | { | |
272 | keyexch *kx = v; | |
273 | kx->f &= ~KXF_TIMER; | |
274 | T( trace(T_KEYEXCH, "keyexch: timer has popped"); ) | |
de014da6 | 275 | kx_start(kx, 0); |
410c8acf | 276 | } |
277 | ||
278 | /* --- @settimer@ --- * | |
279 | * | |
280 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
ff143952 | 281 | * @struct timeval *tv@ = when to set the timer for |
410c8acf | 282 | * |
283 | * Returns: --- | |
284 | * | |
285 | * Use: Sets the timer for the next key exchange attempt. | |
286 | */ | |
287 | ||
ff143952 | 288 | static void settimer(keyexch *kx, struct timeval *tv) |
410c8acf | 289 | { |
ff143952 MW |
290 | if (kx->f & KXF_TIMER) sel_rmtimer(&kx->t); |
291 | sel_addtimer(&sel, &kx->t, tv, timer, kx); | |
410c8acf | 292 | kx->f |= KXF_TIMER; |
293 | } | |
294 | ||
a06d57a3 MW |
295 | /* --- @f2tv@ --- * |
296 | * | |
297 | * Arguments: @struct timeval *tv@ = where to write the timeval | |
298 | * @double t@ = a time as a floating point number | |
299 | * | |
300 | * Returns: --- | |
301 | * | |
302 | * Use: Converts a floating-point time into a timeval. | |
303 | */ | |
304 | ||
305 | static void f2tv(struct timeval *tv, double t) | |
306 | { | |
307 | tv->tv_sec = t; | |
308 | tv->tv_usec = (t - tv->tv_sec)*MILLION; | |
309 | } | |
310 | ||
311 | /* --- @wobble@ --- * | |
312 | * | |
313 | * Arguments: @double t@ = a time interval | |
314 | * | |
315 | * Returns: The same time interval, with a random error applied. | |
316 | */ | |
317 | ||
318 | static double wobble(double t) | |
319 | { | |
320 | uint32 r = rand_global.ops->word(&rand_global); | |
321 | double w = (r/F_2P32) - 0.5; | |
322 | return (t + t*w*T_WOBBLE); | |
323 | } | |
324 | ||
325 | /* --- @rs_time@ --- * | |
326 | * | |
327 | * Arguments: @retry *rs@ = current retry state | |
328 | * @struct timeval *tv@ = where to write the result | |
329 | * @const struct timeval *now@ = current time, or null | |
330 | * | |
331 | * Returns: --- | |
332 | * | |
333 | * Use: Computes a time at which to retry sending a key-exchange | |
334 | * packet. This algorithm is subject to change, but it's | |
335 | * currently a capped exponential backoff, slightly randomized | |
336 | * to try to keep clients from hammering a server that's only | |
337 | * just woken up. | |
338 | * | |
339 | * If @now@ is null then the function works out the time for | |
340 | * itself. | |
341 | */ | |
342 | ||
343 | static void rs_time(retry *rs, struct timeval *tv, const struct timeval *now) | |
344 | { | |
345 | double t; | |
346 | struct timeval rtv; | |
347 | ||
348 | if (!rs->t) | |
349 | t = SEC(2); | |
350 | else { | |
351 | t = (rs->t * 5)/4; | |
352 | if (t > MIN(5)) t = MIN(5); | |
353 | } | |
354 | rs->t = t; | |
355 | ||
356 | if (!now) { | |
357 | now = tv; | |
358 | gettimeofday(tv, 0); | |
359 | } | |
360 | f2tv(&rtv, wobble(t)); | |
361 | TV_ADD(tv, now, &rtv); | |
362 | } | |
363 | ||
364 | /* --- @retry_reset@ --- * | |
365 | * | |
366 | * Arguments: @retry *rs@ = retry state | |
367 | * | |
368 | * Returns: -- | |
369 | * | |
370 | * Use: Resets a retry state to indicate that progress has been | |
371 | * made. Also useful for initializing the state in the first | |
372 | * place. | |
373 | */ | |
374 | ||
375 | static void rs_reset(retry *rs) { rs->t = 0; } | |
376 | ||
0617b6e7 | 377 | /*----- Challenge management ----------------------------------------------*/ |
378 | ||
379 | /* --- Notes on challenge management --- * | |
410c8acf | 380 | * |
0617b6e7 | 381 | * We may get multiple different replies to our key exchange; some will be |
382 | * correct, some inserted by attackers. Up until @KX_THRESH@, all challenges | |
383 | * received will be added to the table and given a full response. After | |
384 | * @KX_THRESH@ distinct challenges are received, we return only a `cookie': | |
385 | * our existing challenge, followed by a hash of the sender's challenge. We | |
386 | * do %%\emph{not}%% give a bare challenge a reply slot at this stage. All | |
387 | * properly-formed cookies are assigned a table slot: if none is spare, a | |
388 | * used slot is randomly selected and destroyed. A cookie always receives a | |
389 | * full reply. | |
390 | */ | |
391 | ||
392 | /* --- @kxc_destroy@ --- * | |
393 | * | |
394 | * Arguments: @kxchal *kxc@ = pointer to the challenge block | |
410c8acf | 395 | * |
396 | * Returns: --- | |
397 | * | |
0617b6e7 | 398 | * Use: Disposes of a challenge block. |
410c8acf | 399 | */ |
400 | ||
0617b6e7 | 401 | static void kxc_destroy(kxchal *kxc) |
410c8acf | 402 | { |
5b9f3d37 | 403 | const dhgrp *g = kxc->kx->kpriv->grp; |
0617b6e7 | 404 | if (kxc->f & KXF_TIMER) |
405 | sel_rmtimer(&kxc->t); | |
5b9f3d37 MW |
406 | g->ops->freege(g, kxc->C); |
407 | g->ops->freege(g, kxc->R); | |
0617b6e7 | 408 | ks_drop(kxc->ks); |
409 | DESTROY(kxc); | |
410 | } | |
410c8acf | 411 | |
0617b6e7 | 412 | /* --- @kxc_stoptimer@ --- * |
413 | * | |
414 | * Arguments: @kxchal *kxc@ = pointer to the challenge block | |
415 | * | |
416 | * Returns: --- | |
417 | * | |
418 | * Use: Stops the challenge's retry timer from sending messages. | |
419 | * Useful when the state machine is in the endgame of the | |
420 | * exchange. | |
421 | */ | |
410c8acf | 422 | |
0617b6e7 | 423 | static void kxc_stoptimer(kxchal *kxc) |
424 | { | |
425 | if (kxc->f & KXF_TIMER) | |
426 | sel_rmtimer(&kxc->t); | |
2de0ad0f | 427 | kxc->f &= ~KXF_TIMER; |
0617b6e7 | 428 | } |
410c8acf | 429 | |
0617b6e7 | 430 | /* --- @kxc_new@ --- * |
431 | * | |
432 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
0617b6e7 | 433 | * |
434 | * Returns: A pointer to the challenge block. | |
435 | * | |
436 | * Use: Returns a pointer to a new challenge block to fill in. | |
705ecf30 MW |
437 | * In particular, the @c@ and @r@ members are left |
438 | * uninitialized. | |
0617b6e7 | 439 | */ |
410c8acf | 440 | |
0617b6e7 | 441 | static kxchal *kxc_new(keyexch *kx) |
442 | { | |
443 | kxchal *kxc; | |
444 | unsigned i; | |
445 | ||
446 | /* --- If we're over reply threshold, discard one at random --- */ | |
447 | ||
448 | if (kx->nr < KX_NCHAL) | |
449 | i = kx->nr++; | |
450 | else { | |
451 | i = rand_global.ops->range(&rand_global, KX_NCHAL); | |
452 | kxc_destroy(kx->r[i]); | |
410c8acf | 453 | } |
454 | ||
0617b6e7 | 455 | /* --- Fill in the new structure --- */ |
410c8acf | 456 | |
0617b6e7 | 457 | kxc = CREATE(kxchal); |
0617b6e7 | 458 | kxc->ks = 0; |
459 | kxc->kx = kx; | |
460 | kxc->f = 0; | |
461 | kx->r[i] = kxc; | |
a06d57a3 | 462 | rs_reset(&kxc->rs); |
0617b6e7 | 463 | return (kxc); |
464 | } | |
410c8acf | 465 | |
0617b6e7 | 466 | /* --- @kxc_bychal@ --- * |
467 | * | |
468 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
5b9f3d37 | 469 | * @const dhge *C@ = challenge from remote host |
0617b6e7 | 470 | * |
471 | * Returns: Pointer to the challenge block, or null. | |
472 | * | |
473 | * Use: Finds a challenge block, given its challenge. | |
474 | */ | |
475 | ||
5b9f3d37 | 476 | static kxchal *kxc_bychal(keyexch *kx, const dhge *C) |
0617b6e7 | 477 | { |
5b9f3d37 | 478 | const dhgrp *g = kx->kpriv->grp; |
0617b6e7 | 479 | unsigned i; |
480 | ||
481 | for (i = 0; i < kx->nr; i++) { | |
5b9f3d37 | 482 | if (g->ops->eq(g, C, kx->r[i]->C)) |
0617b6e7 | 483 | return (kx->r[i]); |
484 | } | |
485 | return (0); | |
486 | } | |
487 | ||
488 | /* --- @kxc_byhc@ --- * | |
489 | * | |
490 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
491 | * @const octet *hc@ = challenge hash from remote host | |
492 | * | |
493 | * Returns: Pointer to the challenge block, or null. | |
494 | * | |
495 | * Use: Finds a challenge block, given a hash of its challenge. | |
496 | */ | |
410c8acf | 497 | |
0617b6e7 | 498 | static kxchal *kxc_byhc(keyexch *kx, const octet *hc) |
499 | { | |
500 | unsigned i; | |
501 | ||
502 | for (i = 0; i < kx->nr; i++) { | |
35c8b547 | 503 | if (memcmp(hc, kx->r[i]->hc, kx->kpriv->algs.hashsz) == 0) |
0617b6e7 | 504 | return (kx->r[i]); |
410c8acf | 505 | } |
0617b6e7 | 506 | return (0); |
507 | } | |
508 | ||
509 | /* --- @kxc_answer@ --- * | |
510 | * | |
511 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
512 | * @kxchal *kxc@ = pointer to challenge block | |
513 | * | |
514 | * Returns: --- | |
515 | * | |
516 | * Use: Sends a reply to the remote host, according to the data in | |
517 | * this challenge block. | |
518 | */ | |
519 | ||
520 | static void kxc_answer(keyexch *kx, kxchal *kxc); | |
521 | ||
522 | static void kxc_timer(struct timeval *tv, void *v) | |
523 | { | |
524 | kxchal *kxc = v; | |
525 | kxc->f &= ~KXF_TIMER; | |
526 | kxc_answer(kxc->kx, kxc); | |
527 | } | |
528 | ||
529 | static void kxc_answer(keyexch *kx, kxchal *kxc) | |
530 | { | |
531 | stats *st = p_stats(kx->p); | |
de7bd20b | 532 | buf *b = p_txstart(kx->p, MSG_KEYEXCH | KX_REPLY); |
5b9f3d37 | 533 | const dhgrp *g = kx->kpriv->grp; |
0617b6e7 | 534 | struct timeval tv; |
535 | buf bb; | |
536 | ||
537 | /* --- Build the reply packet --- */ | |
538 | ||
de7bd20b | 539 | T( trace(T_KEYEXCH, "keyexch: sending reply to `%s'", p_name(kx->p)); ) |
5b9f3d37 | 540 | sendchallenge(kx, b, kxc->C, kxc->hc); |
de7bd20b | 541 | buf_init(&bb, buf_i, sizeof(buf_i)); |
5b9f3d37 | 542 | g->ops->stge(g, &bb, kxc->R, DHFMT_STD); |
de7bd20b MW |
543 | buf_flip(&bb); |
544 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_REPLY, &bb, b); | |
0617b6e7 | 545 | |
546 | /* --- Update the statistics --- */ | |
547 | ||
548 | if (BOK(b)) { | |
549 | st->n_kxout++; | |
550 | st->sz_kxout += BLEN(b); | |
551 | p_txend(kx->p); | |
552 | } | |
553 | ||
554 | /* --- Schedule another resend --- */ | |
555 | ||
556 | if (kxc->f & KXF_TIMER) | |
557 | sel_rmtimer(&kxc->t); | |
558 | gettimeofday(&tv, 0); | |
a06d57a3 | 559 | rs_time(&kxc->rs, &tv, &tv); |
0617b6e7 | 560 | sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc); |
561 | kxc->f |= KXF_TIMER; | |
562 | } | |
563 | ||
564 | /*----- Individual message handlers ---------------------------------------*/ | |
565 | ||
de7bd20b | 566 | /* --- @doprechallenge@ --- * |
0617b6e7 | 567 | * |
de7bd20b MW |
568 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
569 | * @buf *b@ = buffer containing the packet | |
0617b6e7 | 570 | * |
de7bd20b | 571 | * Returns: Zero if OK, nonzero of the packet was rejected. |
0617b6e7 | 572 | * |
de7bd20b | 573 | * Use: Processes a pre-challenge message. |
0617b6e7 | 574 | */ |
575 | ||
de7bd20b | 576 | static int doprechallenge(keyexch *kx, buf *b) |
0617b6e7 | 577 | { |
de7bd20b | 578 | stats *st = p_stats(kx->p); |
5b9f3d37 MW |
579 | const dhgrp *g = kx->kpriv->grp; |
580 | dhge *C = 0; | |
b5c45da1 | 581 | ghash *h; |
0617b6e7 | 582 | |
de7bd20b MW |
583 | /* --- Ensure that we're in a sensible state --- */ |
584 | ||
585 | if (kx->s != KXS_CHAL) { | |
586 | a_warn("KX", "?PEER", kx->p, "unexpected", "pre-challenge", A_END); | |
587 | goto bad; | |
588 | } | |
589 | ||
590 | /* --- Unpack the packet --- */ | |
591 | ||
5b9f3d37 | 592 | if ((C = g->ops->ldge(g, b, DHFMT_VAR)) == 0 || BLEFT(b)) |
de7bd20b | 593 | goto bad; |
b5c45da1 | 594 | |
0617b6e7 | 595 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
5b9f3d37 | 596 | trace(T_CRYPTO, "crypto: challenge = %s", g->ops->gestr(g, C)); |
0617b6e7 | 597 | })) |
de7bd20b MW |
598 | |
599 | /* --- Send out a full challenge by return --- */ | |
600 | ||
601 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_CHAL); | |
35c8b547 | 602 | h = GH_INIT(kx->kpriv->algs.h); |
de7bd20b | 603 | HASH_STRING(h, "tripe-cookie"); |
5b9f3d37 MW |
604 | hashge(h, g, C); |
605 | sendchallenge(kx, b, C, GH_DONE(h, 0)); | |
b5c45da1 | 606 | GH_DESTROY(h); |
de7bd20b MW |
607 | st->n_kxout++; |
608 | st->sz_kxout += BLEN(b); | |
609 | p_txend(kx->p); | |
610 | ||
611 | /* --- Done --- */ | |
612 | ||
5b9f3d37 | 613 | g->ops->freege(g, C); |
de7bd20b MW |
614 | return (0); |
615 | ||
616 | bad: | |
5b9f3d37 | 617 | if (C) g->ops->freege(g, C); |
de7bd20b | 618 | return (-1); |
0617b6e7 | 619 | } |
620 | ||
de7bd20b | 621 | /* --- @respond@ --- * |
0617b6e7 | 622 | * |
623 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
de7bd20b | 624 | * @unsigned msg@ = message code for this packet |
0617b6e7 | 625 | * @buf *b@ = buffer containing the packet |
626 | * | |
de7bd20b | 627 | * Returns: Key-exchange challenge block, or null. |
0617b6e7 | 628 | * |
de7bd20b MW |
629 | * Use: Computes a response for the given challenge, entering it into |
630 | * a challenge block and so on. | |
0617b6e7 | 631 | */ |
632 | ||
de7bd20b | 633 | static kxchal *respond(keyexch *kx, unsigned msg, buf *b) |
0617b6e7 | 634 | { |
5b9f3d37 | 635 | const dhgrp *g = kx->kpriv->grp; |
35c8b547 | 636 | const algswitch *algs = &kx->kpriv->algs; |
5b9f3d37 MW |
637 | size_t ixsz = g->scsz; |
638 | dhge *C = 0; | |
639 | dhge *R = 0; | |
640 | dhge *CC = 0; | |
de7bd20b MW |
641 | const octet *hc, *ck; |
642 | size_t x, y, z; | |
5b9f3d37 | 643 | dhsc *c = 0; |
0617b6e7 | 644 | kxchal *kxc; |
de7bd20b MW |
645 | ghash *h = 0; |
646 | buf bb; | |
647 | int ok; | |
0617b6e7 | 648 | |
649 | /* --- Unpack the packet --- */ | |
650 | ||
5b9f3d37 | 651 | if ((C = g->ops->ldge(g, b, DHFMT_VAR)) == 0 || |
35c8b547 MW |
652 | (hc = buf_get(b, algs->hashsz)) == 0 || |
653 | (ck = buf_get(b, ixsz)) == 0) { | |
f43df819 | 654 | a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); |
0617b6e7 | 655 | goto bad; |
656 | } | |
0617b6e7 | 657 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
5b9f3d37 | 658 | trace(T_CRYPTO, "crypto: challenge = %s", g->ops->gestr(g, C)); |
35c8b547 MW |
659 | trace_block(T_CRYPTO, "crypto: cookie", hc, algs->hashsz); |
660 | trace_block(T_CRYPTO, "crypto: check-value", ck, ixsz); | |
0617b6e7 | 661 | })) |
662 | ||
0617b6e7 | 663 | /* --- Discard a packet with an invalid cookie --- */ |
664 | ||
35c8b547 | 665 | if (hc && memcmp(hc, kx->hc, algs->hashsz) != 0) { |
5ac9463b | 666 | a_warn("KX", "?PEER", kx->p, "incorrect", "cookie", A_END); |
0617b6e7 | 667 | goto bad; |
668 | } | |
669 | ||
de7bd20b MW |
670 | /* --- Recover the check value and verify it --- * |
671 | * | |
672 | * To avoid recomputation on replays, we store a hash of the `right' | |
673 | * value. The `correct' value is unique, so this is right. | |
410c8acf | 674 | * |
de7bd20b | 675 | * This will also find a challenge block and, if necessary, populate it. |
410c8acf | 676 | */ |
677 | ||
5b9f3d37 | 678 | if ((kxc = kxc_bychal(kx, C)) != 0) { |
35c8b547 | 679 | h = GH_INIT(algs->h); |
de7bd20b | 680 | HASH_STRING(h, "tripe-check-hash"); |
35c8b547 MW |
681 | GH_HASH(h, ck, ixsz); |
682 | ok = !memcmp(kxc->ck, GH_DONE(h, 0), algs->hashsz); | |
de7bd20b MW |
683 | GH_DESTROY(h); |
684 | if (!ok) goto badcheck; | |
685 | } else { | |
686 | ||
687 | /* --- Compute the reply, and check the magic --- */ | |
688 | ||
5b9f3d37 MW |
689 | R = g->ops->mul(g, kx->kpriv->k, C); |
690 | if ((c = mpunmask(g, ck, ixsz, algs->mgf, | |
691 | hashcheck(kx, kx->kpub->K, kx->C, C, R), | |
692 | algs->hashsz)) == 0) | |
c13541b1 | 693 | goto badcheck; |
de7bd20b | 694 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
5b9f3d37 MW |
695 | trace(T_CRYPTO, "crypto: computed reply = %s", g->ops->gestr(g, R)); |
696 | trace(T_CRYPTO, "crypto: recovered log = %s", g->ops->scstr(g, c)); | |
de7bd20b | 697 | })) |
5b9f3d37 MW |
698 | CC = g->ops->mul(g, c, 0); |
699 | if (!g->ops->eq(g, CC, C)) goto badcheck; | |
de7bd20b MW |
700 | |
701 | /* --- Fill in a new challenge block --- */ | |
e04c2d50 | 702 | |
de7bd20b | 703 | kxc = kxc_new(kx); |
5b9f3d37 MW |
704 | kxc->C = C; C = 0; |
705 | kxc->R = R; R = 0; | |
0617b6e7 | 706 | |
35c8b547 MW |
707 | h = GH_INIT(algs->h); HASH_STRING(h, "tripe-check-hash"); |
708 | GH_HASH(h, ck, ixsz); | |
709 | GH_DONE(h, kxc->ck); GH_DESTROY(h); | |
0617b6e7 | 710 | |
35c8b547 | 711 | h = GH_INIT(algs->h); HASH_STRING(h, "tripe-cookie"); |
5b9f3d37 | 712 | hashge(h, g, kxc->C); |
35c8b547 | 713 | GH_DONE(h, kxc->hc); GH_DESTROY(h); |
b5c45da1 | 714 | |
715 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
35c8b547 MW |
716 | trace_block(T_CRYPTO, "crypto: computed cookie", |
717 | kxc->hc, algs->hashsz); | |
b5c45da1 | 718 | })) |
0617b6e7 | 719 | |
0617b6e7 | 720 | /* --- Work out the shared key --- */ |
721 | ||
5b9f3d37 | 722 | R = g->ops->mul(g, kx->a, kxc->C); |
b5c45da1 | 723 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
5b9f3d37 | 724 | trace(T_CRYPTO, "crypto: shared secret = %s", g->ops->gestr(g, R)); |
b5c45da1 | 725 | })) |
0617b6e7 | 726 | |
727 | /* --- Compute the switch messages --- */ | |
728 | ||
35c8b547 | 729 | h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-request"); |
5b9f3d37 | 730 | hashge(h, g, kx->C); hashge(h, g, kxc->C); |
b5c45da1 | 731 | GH_DONE(h, kxc->hswrq_out); GH_DESTROY(h); |
35c8b547 | 732 | h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-confirm"); |
5b9f3d37 | 733 | hashge(h, g, kx->C); hashge(h, g, kxc->C); |
b5c45da1 | 734 | GH_DONE(h, kxc->hswok_out); GH_DESTROY(h); |
0617b6e7 | 735 | |
35c8b547 | 736 | h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-request"); |
5b9f3d37 | 737 | hashge(h, g, kxc->C); hashge(h, g, kx->C); |
b5c45da1 | 738 | GH_DONE(h, kxc->hswrq_in); GH_DESTROY(h); |
35c8b547 | 739 | h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-confirm"); |
5b9f3d37 | 740 | hashge(h, g, kxc->C); hashge(h, g, kx->C); |
b5c45da1 | 741 | GH_DONE(h, kxc->hswok_in); GH_DESTROY(h); |
0617b6e7 | 742 | |
743 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
0617b6e7 | 744 | trace_block(T_CRYPTO, "crypto: outbound switch request", |
35c8b547 | 745 | kxc->hswrq_out, algs->hashsz); |
0617b6e7 | 746 | trace_block(T_CRYPTO, "crypto: outbound switch confirm", |
35c8b547 | 747 | kxc->hswok_out, algs->hashsz); |
0617b6e7 | 748 | trace_block(T_CRYPTO, "crypto: inbound switch request", |
35c8b547 | 749 | kxc->hswrq_in, algs->hashsz); |
0617b6e7 | 750 | trace_block(T_CRYPTO, "crypto: inbound switch confirm", |
35c8b547 | 751 | kxc->hswok_in, algs->hashsz); |
0617b6e7 | 752 | })) |
753 | ||
754 | /* --- Create a new symmetric keyset --- */ | |
755 | ||
de7bd20b | 756 | buf_init(&bb, buf_o, sizeof(buf_o)); |
5b9f3d37 MW |
757 | g->ops->stge(g, &bb, kx->C, DHFMT_HASH); x = BLEN(&bb); |
758 | g->ops->stge(g, &bb, kxc->C, DHFMT_HASH); y = BLEN(&bb); | |
759 | g->ops->stge(g, &bb, R, DHFMT_HASH); z = BLEN(&bb); | |
de7bd20b | 760 | assert(BOK(&bb)); |
0617b6e7 | 761 | |
de7bd20b | 762 | kxc->ks = ks_gen(BBASE(&bb), x, y, z, kx->p); |
410c8acf | 763 | } |
764 | ||
5b9f3d37 MW |
765 | if (C) g->ops->freege(g, C); |
766 | if (CC) g->ops->freege(g, CC); | |
767 | if (R) g->ops->freege(g, R); | |
768 | if (c) g->ops->freesc(g, c); | |
de7bd20b | 769 | return (kxc); |
410c8acf | 770 | |
de7bd20b MW |
771 | badcheck: |
772 | a_warn("KX", "?PEER", kx->p, "bad-expected-reply-log", A_END); | |
773 | goto bad; | |
774 | bad: | |
5b9f3d37 MW |
775 | if (C) g->ops->freege(g, C); |
776 | if (CC) g->ops->freege(g, CC); | |
777 | if (R) g->ops->freege(g, R); | |
778 | if (c) g->ops->freesc(g, c); | |
e04c2d50 | 779 | return (0); |
de7bd20b | 780 | } |
0617b6e7 | 781 | |
de7bd20b MW |
782 | /* --- @dochallenge@ --- * |
783 | * | |
784 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
785 | * @unsigned msg@ = message code for the packet | |
786 | * @buf *b@ = buffer containing the packet | |
787 | * | |
788 | * Returns: Zero if OK, nonzero if the packet was rejected. | |
789 | * | |
790 | * Use: Processes a packet containing a challenge. | |
791 | */ | |
0617b6e7 | 792 | |
de7bd20b MW |
793 | static int dochallenge(keyexch *kx, buf *b) |
794 | { | |
795 | kxchal *kxc; | |
0617b6e7 | 796 | |
de7bd20b MW |
797 | if (kx->s != KXS_CHAL) { |
798 | a_warn("KX", "?PEER", kx->p, "unexpected", "challenge", A_END); | |
799 | goto bad; | |
800 | } | |
801 | if ((kxc = respond(kx, KX_CHAL, b)) == 0) | |
802 | goto bad; | |
803 | if (BLEFT(b)) { | |
804 | a_warn("KX", "?PEER", kx->p, "invalid", "challenge", A_END); | |
805 | goto bad; | |
806 | } | |
807 | kxc_answer(kx, kxc); | |
0617b6e7 | 808 | return (0); |
809 | ||
810 | bad: | |
0617b6e7 | 811 | return (-1); |
410c8acf | 812 | } |
813 | ||
0617b6e7 | 814 | /* --- @resend@ --- * |
410c8acf | 815 | * |
816 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
410c8acf | 817 | * |
818 | * Returns: --- | |
819 | * | |
0617b6e7 | 820 | * Use: Sends the next message for a key exchange. |
410c8acf | 821 | */ |
822 | ||
0617b6e7 | 823 | static void resend(keyexch *kx) |
410c8acf | 824 | { |
0617b6e7 | 825 | kxchal *kxc; |
826 | buf bb; | |
827 | stats *st = p_stats(kx->p); | |
ff143952 | 828 | struct timeval tv; |
5b9f3d37 | 829 | const dhgrp *g = kx->kpriv->grp; |
410c8acf | 830 | buf *b; |
831 | ||
0617b6e7 | 832 | switch (kx->s) { |
833 | case KXS_CHAL: | |
00e64b67 | 834 | T( trace(T_KEYEXCH, "keyexch: sending prechallenge to `%s'", |
835 | p_name(kx->p)); ) | |
0617b6e7 | 836 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_PRECHAL); |
5b9f3d37 | 837 | g->ops->stge(g, b, kx->C, DHFMT_VAR); |
0617b6e7 | 838 | break; |
839 | case KXS_COMMIT: | |
00e64b67 | 840 | T( trace(T_KEYEXCH, "keyexch: sending switch request to `%s'", |
841 | p_name(kx->p)); ) | |
0617b6e7 | 842 | kxc = kx->r[0]; |
843 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCH); | |
35c8b547 MW |
844 | buf_put(b, kx->hc, kx->kpriv->algs.hashsz); |
845 | buf_put(b, kxc->hc, kx->kpriv->algs.hashsz); | |
0617b6e7 | 846 | buf_init(&bb, buf_i, sizeof(buf_i)); |
5b9f3d37 | 847 | g->ops->stge(g, &bb, kxc->R, DHFMT_STD); |
35c8b547 | 848 | buf_put(&bb, kxc->hswrq_out, kx->kpriv->algs.hashsz); |
0617b6e7 | 849 | buf_flip(&bb); |
7ed14135 | 850 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCH, &bb, b); |
0617b6e7 | 851 | break; |
852 | case KXS_SWITCH: | |
00e64b67 | 853 | T( trace(T_KEYEXCH, "keyexch: sending switch confirmation to `%s'", |
0617b6e7 | 854 | p_name(kx->p)); ) |
855 | kxc = kx->r[0]; | |
856 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCHOK); | |
857 | buf_init(&bb, buf_i, sizeof(buf_i)); | |
35c8b547 | 858 | buf_put(&bb, kxc->hswok_out, kx->kpriv->algs.hashsz); |
0617b6e7 | 859 | buf_flip(&bb); |
7ed14135 | 860 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, &bb, b); |
0617b6e7 | 861 | break; |
862 | default: | |
863 | abort(); | |
410c8acf | 864 | } |
0617b6e7 | 865 | |
866 | if (BOK(b)) { | |
867 | st->n_kxout++; | |
868 | st->sz_kxout += BLEN(b); | |
869 | p_txend(kx->p); | |
870 | } | |
871 | ||
ff143952 | 872 | if (kx->s < KXS_SWITCH) { |
a06d57a3 | 873 | rs_time(&kx->rs, &tv, 0); |
ff143952 MW |
874 | settimer(kx, &tv); |
875 | } | |
410c8acf | 876 | } |
877 | ||
de7bd20b | 878 | /* --- @decryptrest@ --- * |
0617b6e7 | 879 | * |
880 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
de7bd20b MW |
881 | * @kxchal *kxc@ = pointer to challenge block |
882 | * @unsigned msg@ = type of incoming message | |
0617b6e7 | 883 | * @buf *b@ = encrypted remainder of the packet |
884 | * | |
de7bd20b | 885 | * Returns: Zero if OK, nonzero on some kind of error. |
0617b6e7 | 886 | * |
de7bd20b MW |
887 | * Use: Decrypts the remainder of the packet, and points @b@ at the |
888 | * recovered plaintext. | |
0617b6e7 | 889 | */ |
890 | ||
de7bd20b | 891 | static int decryptrest(keyexch *kx, kxchal *kxc, unsigned msg, buf *b) |
410c8acf | 892 | { |
0617b6e7 | 893 | buf bb; |
0617b6e7 | 894 | |
de7bd20b MW |
895 | buf_init(&bb, buf_o, sizeof(buf_o)); |
896 | if (ks_decrypt(kxc->ks, MSG_KEYEXCH | msg, b, &bb)) { | |
897 | a_warn("KX", "?PEER", kx->p, "decrypt-failed", "%s", pkname[msg], A_END); | |
898 | return (-1); | |
0617b6e7 | 899 | } |
12a26b8b | 900 | if (!BOK(&bb)) return (-1); |
de7bd20b MW |
901 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
902 | return (0); | |
903 | } | |
410c8acf | 904 | |
de7bd20b MW |
905 | /* --- @checkresponse@ --- * |
906 | * | |
907 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
908 | * @unsigned msg@ = type of incoming message | |
909 | * @buf *b@ = decrypted remainder of the packet | |
910 | * | |
911 | * Returns: Zero if OK, nonzero on some kind of error. | |
912 | * | |
913 | * Use: Checks a reply or switch packet, ensuring that its response | |
914 | * is correct. | |
915 | */ | |
0617b6e7 | 916 | |
de7bd20b MW |
917 | static int checkresponse(keyexch *kx, unsigned msg, buf *b) |
918 | { | |
5b9f3d37 MW |
919 | const dhgrp *g = kx->kpriv->grp; |
920 | dhge *R; | |
0617b6e7 | 921 | |
5b9f3d37 | 922 | if ((R = g->ops->ldge(g, b, DHFMT_STD)) == 0) { |
de7bd20b | 923 | a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); |
0617b6e7 | 924 | goto bad; |
925 | } | |
926 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { | |
5b9f3d37 | 927 | trace(T_CRYPTO, "crypto: reply = %s", g->ops->gestr(g, R)); |
0617b6e7 | 928 | })) |
5b9f3d37 | 929 | if (!g->ops->eq(g, R, kx->RX)) { |
de7bd20b | 930 | a_warn("KX", "?PEER", kx->p, "incorrect", "response", A_END); |
0617b6e7 | 931 | goto bad; |
932 | } | |
933 | ||
5b9f3d37 | 934 | g->ops->freege(g, R); |
de7bd20b | 935 | return (0); |
0617b6e7 | 936 | |
937 | bad: | |
5b9f3d37 | 938 | if (R) g->ops->freege(g, R); |
de7bd20b | 939 | return (-1); |
410c8acf | 940 | } |
941 | ||
0617b6e7 | 942 | /* --- @commit@ --- * |
410c8acf | 943 | * |
944 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
0617b6e7 | 945 | * @kxchal *kxc@ = pointer to challenge to commit to |
410c8acf | 946 | * |
947 | * Returns: --- | |
948 | * | |
0617b6e7 | 949 | * Use: Commits to a particular challenge as being the `right' one, |
950 | * since a reply has arrived for it. | |
410c8acf | 951 | */ |
952 | ||
0617b6e7 | 953 | static void commit(keyexch *kx, kxchal *kxc) |
410c8acf | 954 | { |
0617b6e7 | 955 | unsigned i; |
410c8acf | 956 | |
0617b6e7 | 957 | for (i = 0; i < kx->nr; i++) { |
958 | if (kx->r[i] != kxc) | |
959 | kxc_destroy(kx->r[i]); | |
960 | } | |
961 | kx->r[0] = kxc; | |
962 | kx->nr = 1; | |
963 | kxc_stoptimer(kxc); | |
e04c2d50 | 964 | ksl_link(kx->ks, kxc->ks); |
410c8acf | 965 | } |
966 | ||
0617b6e7 | 967 | /* --- @doreply@ --- * |
410c8acf | 968 | * |
969 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
0617b6e7 | 970 | * @buf *b@ = buffer containing packet |
410c8acf | 971 | * |
0617b6e7 | 972 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf | 973 | * |
0617b6e7 | 974 | * Use: Handles a reply packet. This doesn't handle the various |
975 | * switch packets: they're rather too different. | |
410c8acf | 976 | */ |
977 | ||
0617b6e7 | 978 | static int doreply(keyexch *kx, buf *b) |
410c8acf | 979 | { |
0617b6e7 | 980 | kxchal *kxc; |
981 | ||
982 | if (kx->s != KXS_CHAL && kx->s != KXS_COMMIT) { | |
f43df819 | 983 | a_warn("KX", "?PEER", kx->p, "unexpected", "reply", A_END); |
0617b6e7 | 984 | goto bad; |
985 | } | |
de7bd20b MW |
986 | if ((kxc = respond(kx, KX_REPLY, b)) == 0 || |
987 | decryptrest(kx, kxc, KX_REPLY, b) || | |
988 | checkresponse(kx, KX_REPLY, b)) | |
0617b6e7 | 989 | goto bad; |
990 | if (BLEFT(b)) { | |
f43df819 | 991 | a_warn("KX", "?PEER", kx->p, "invalid", "reply", A_END); |
0617b6e7 | 992 | goto bad; |
e04c2d50 | 993 | } |
0617b6e7 | 994 | if (kx->s == KXS_CHAL) { |
995 | commit(kx, kxc); | |
996 | kx->s = KXS_COMMIT; | |
997 | } | |
998 | resend(kx); | |
999 | return (0); | |
1000 | ||
1001 | bad: | |
1002 | return (-1); | |
410c8acf | 1003 | } |
1004 | ||
3cdc3f3a | 1005 | /* --- @kxfinish@ --- * |
1006 | * | |
1007 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
1008 | * | |
1009 | * Returns: --- | |
1010 | * | |
1011 | * Use: Sets everything up following a successful key exchange. | |
1012 | */ | |
1013 | ||
1014 | static void kxfinish(keyexch *kx) | |
1015 | { | |
1016 | kxchal *kxc = kx->r[0]; | |
a06d57a3 | 1017 | struct timeval now, tv; |
ff143952 | 1018 | |
3cdc3f3a | 1019 | ks_activate(kxc->ks); |
a06d57a3 MW |
1020 | gettimeofday(&now, 0); |
1021 | f2tv(&tv, wobble(T_REGEN)); | |
1022 | TV_ADD(&tv, &now, &tv); | |
ff143952 | 1023 | settimer(kx, &tv); |
3cdc3f3a | 1024 | kx->s = KXS_SWITCH; |
f43df819 | 1025 | a_notify("KXDONE", "?PEER", kx->p, A_END); |
3cdc3f3a | 1026 | p_stats(kx->p)->t_kx = time(0); |
1027 | } | |
1028 | ||
0617b6e7 | 1029 | /* --- @doswitch@ --- * |
410c8acf | 1030 | * |
0617b6e7 | 1031 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
1032 | * @buf *b@ = pointer to buffer containing packet | |
410c8acf | 1033 | * |
0617b6e7 | 1034 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf | 1035 | * |
0617b6e7 | 1036 | * Use: Handles a reply with a switch request bolted onto it. |
410c8acf | 1037 | */ |
1038 | ||
0617b6e7 | 1039 | static int doswitch(keyexch *kx, buf *b) |
410c8acf | 1040 | { |
35c8b547 | 1041 | size_t hsz = kx->kpriv->algs.hashsz; |
0617b6e7 | 1042 | const octet *hc_in, *hc_out, *hswrq; |
1043 | kxchal *kxc; | |
410c8acf | 1044 | |
35c8b547 MW |
1045 | if ((hc_in = buf_get(b, hsz)) == 0 || |
1046 | (hc_out = buf_get(b, hsz)) == 0) { | |
f43df819 | 1047 | a_warn("KX", "?PEER", kx->p, "invalid", "switch-rq", A_END); |
0617b6e7 | 1048 | goto bad; |
410c8acf | 1049 | } |
de7bd20b | 1050 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
35c8b547 MW |
1051 | trace_block(T_CRYPTO, "crypto: challenge", hc_in, hsz); |
1052 | trace_block(T_CRYPTO, "crypto: cookie", hc_out, hsz); | |
de7bd20b MW |
1053 | })) |
1054 | if ((kxc = kxc_byhc(kx, hc_in)) == 0 || | |
35c8b547 | 1055 | memcmp(hc_out, kx->hc, hsz) != 0) { |
de7bd20b MW |
1056 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); |
1057 | goto bad; | |
1058 | } | |
1059 | if (decryptrest(kx, kxc, KX_SWITCH, b) || | |
1060 | checkresponse(kx, KX_SWITCH, b)) | |
0617b6e7 | 1061 | goto bad; |
35c8b547 | 1062 | if ((hswrq = buf_get(b, hsz)) == 0 || BLEFT(b)) { |
5ac9463b | 1063 | a_warn("KX", "?PEER", kx->p, "invalid", "switch-rq", A_END); |
0617b6e7 | 1064 | goto bad; |
1065 | } | |
1066 | IF_TRACING(T_KEYEXCH, { | |
35c8b547 | 1067 | trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, hsz); |
0617b6e7 | 1068 | }) |
35c8b547 | 1069 | if (memcmp(hswrq, kxc->hswrq_in, hsz) != 0) { |
f43df819 | 1070 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); |
0617b6e7 | 1071 | goto bad; |
1072 | } | |
de7bd20b MW |
1073 | if (kx->s == KXS_CHAL) |
1074 | commit(kx, kxc); | |
1075 | if (kx->s < KXS_SWITCH) | |
1076 | kxfinish(kx); | |
0617b6e7 | 1077 | resend(kx); |
1078 | return (0); | |
1079 | ||
1080 | bad: | |
1081 | return (-1); | |
410c8acf | 1082 | } |
1083 | ||
0617b6e7 | 1084 | /* --- @doswitchok@ --- * |
1085 | * | |
1086 | * Arguments: @keyexch *kx@ = pointer to key exchange block | |
1087 | * @buf *b@ = pointer to buffer containing packet | |
1088 | * | |
1089 | * Returns: Zero if OK, nonzero if the packet was rejected. | |
1090 | * | |
1091 | * Use: Handles a reply with a switch request bolted onto it. | |
1092 | */ | |
1093 | ||
1094 | static int doswitchok(keyexch *kx, buf *b) | |
410c8acf | 1095 | { |
35c8b547 | 1096 | size_t hsz = kx->kpriv->algs.hashsz; |
0617b6e7 | 1097 | const octet *hswok; |
1098 | kxchal *kxc; | |
1099 | buf bb; | |
410c8acf | 1100 | |
0617b6e7 | 1101 | if (kx->s < KXS_COMMIT) { |
f43df819 | 1102 | a_warn("KX", "?PEER", kx->p, "unexpected", "switch-ok", A_END); |
0617b6e7 | 1103 | goto bad; |
410c8acf | 1104 | } |
0617b6e7 | 1105 | kxc = kx->r[0]; |
1106 | buf_init(&bb, buf_o, sizeof(buf_o)); | |
de7bd20b | 1107 | if (decryptrest(kx, kxc, KX_SWITCHOK, b)) |
0617b6e7 | 1108 | goto bad; |
35c8b547 | 1109 | if ((hswok = buf_get(b, hsz)) == 0 || BLEFT(b)) { |
5ac9463b | 1110 | a_warn("KX", "?PEER", kx->p, "invalid", "switch-ok", A_END); |
0617b6e7 | 1111 | goto bad; |
1112 | } | |
1113 | IF_TRACING(T_KEYEXCH, { | |
b5c45da1 | 1114 | trace_block(T_CRYPTO, "crypto: switch confirmation hash", |
35c8b547 | 1115 | hswok, hsz); |
0617b6e7 | 1116 | }) |
35c8b547 | 1117 | if (memcmp(hswok, kxc->hswok_in, hsz) != 0) { |
f43df819 | 1118 | a_warn("KX", "?PEER", kx->p, "incorrect", "switch-ok", A_END); |
0617b6e7 | 1119 | goto bad; |
1120 | } | |
3cdc3f3a | 1121 | if (kx->s < KXS_SWITCH) |
1122 | kxfinish(kx); | |
0617b6e7 | 1123 | return (0); |
1124 | ||
1125 | bad: | |
e04c2d50 | 1126 | return (-1); |
0617b6e7 | 1127 | } |
1128 | ||
1129 | /*----- Main code ---------------------------------------------------------*/ | |
1130 | ||
1131 | /* --- @stop@ --- * | |
1132 | * | |
1133 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1134 | * | |
1135 | * Returns: --- | |
1136 | * | |
1137 | * Use: Stops a key exchange dead in its tracks. Throws away all of | |
1138 | * the context information. The context is left in an | |
1139 | * inconsistent state. The only functions which understand this | |
1140 | * state are @kx_free@ and @kx_init@ (which cause it internally | |
1141 | * it), and @start@ (which expects it to be the prevailing | |
1142 | * state). | |
1143 | */ | |
1144 | ||
1145 | static void stop(keyexch *kx) | |
1146 | { | |
5b9f3d37 | 1147 | const dhgrp *g = kx->kpriv->grp; |
0617b6e7 | 1148 | unsigned i; |
1149 | ||
00e64b67 | 1150 | if (kx->f & KXF_DEAD) |
1151 | return; | |
1152 | ||
0617b6e7 | 1153 | if (kx->f & KXF_TIMER) |
1154 | sel_rmtimer(&kx->t); | |
1155 | for (i = 0; i < kx->nr; i++) | |
1156 | kxc_destroy(kx->r[i]); | |
5b9f3d37 MW |
1157 | g->ops->freesc(g, kx->a); |
1158 | g->ops->freege(g, kx->C); | |
1159 | g->ops->freege(g, kx->RX); | |
00e64b67 | 1160 | kx->t_valid = 0; |
1161 | kx->f |= KXF_DEAD; | |
1162 | kx->f &= ~KXF_TIMER; | |
0617b6e7 | 1163 | } |
1164 | ||
1165 | /* --- @start@ --- * | |
1166 | * | |
1167 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1168 | * @time_t now@ = the current time | |
1169 | * | |
1170 | * Returns: --- | |
1171 | * | |
1172 | * Use: Starts a new key exchange with the peer. The context must be | |
1173 | * in the bizarre state left by @stop@ or @kx_init@. | |
1174 | */ | |
1175 | ||
1176 | static void start(keyexch *kx, time_t now) | |
1177 | { | |
35c8b547 | 1178 | algswitch *algs = &kx->kpriv->algs; |
5b9f3d37 | 1179 | const dhgrp *g = kx->kpriv->grp; |
b5c45da1 | 1180 | ghash *h; |
0617b6e7 | 1181 | |
00e64b67 | 1182 | assert(kx->f & KXF_DEAD); |
1183 | ||
010e6f63 | 1184 | kx->f &= ~(KXF_DEAD | KXF_CORK); |
0617b6e7 | 1185 | kx->nr = 0; |
5b9f3d37 MW |
1186 | kx->a = g->ops->randsc(g); |
1187 | kx->C = g->ops->mul(g, kx->a, 0); | |
1188 | kx->RX = g->ops->mul(g, kx->a, kx->kpub->K); | |
0617b6e7 | 1189 | kx->s = KXS_CHAL; |
1190 | kx->t_valid = now + T_VALID; | |
1191 | ||
35c8b547 | 1192 | h = GH_INIT(algs->h); |
b5c45da1 | 1193 | HASH_STRING(h, "tripe-cookie"); |
5b9f3d37 | 1194 | hashge(h, g, kx->C); |
b5c45da1 | 1195 | GH_DONE(h, kx->hc); |
1196 | GH_DESTROY(h); | |
0617b6e7 | 1197 | |
1198 | IF_TRACING(T_KEYEXCH, { | |
1199 | trace(T_KEYEXCH, "keyexch: creating new challenge"); | |
1200 | IF_TRACING(T_CRYPTO, { | |
5b9f3d37 MW |
1201 | trace(T_CRYPTO, "crypto: secret = %s", g->ops->scstr(g, kx->a)); |
1202 | trace(T_CRYPTO, "crypto: challenge = %s", g->ops->gestr(g, kx->C)); | |
1203 | trace(T_CRYPTO, "crypto: expected response = %s", | |
1204 | g->ops->gestr(g, kx->RX)); | |
35c8b547 MW |
1205 | trace_block(T_CRYPTO, "crypto: challenge cookie", |
1206 | kx->hc, algs->hashsz); | |
0617b6e7 | 1207 | }) |
1208 | }) | |
410c8acf | 1209 | } |
1210 | ||
00e64b67 | 1211 | /* --- @checkpub@ --- * |
1212 | * | |
1213 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1214 | * | |
1215 | * Returns: Zero if OK, nonzero if the peer's public key has expired. | |
1216 | * | |
1217 | * Use: Deactivates the key-exchange until the peer acquires a new | |
1218 | * public key. | |
1219 | */ | |
1220 | ||
1221 | static int checkpub(keyexch *kx) | |
1222 | { | |
1223 | time_t now; | |
35c8b547 MW |
1224 | unsigned f = 0; |
1225 | ||
00e64b67 | 1226 | if (kx->f & KXF_DEAD) |
1227 | return (-1); | |
1228 | now = time(0); | |
35c8b547 MW |
1229 | if (KEY_EXPIRED(now, kx->kpriv->t_exp)) f |= 1; |
1230 | if (KEY_EXPIRED(now, kx->kpub->t_exp)) f |= 2; | |
1231 | if (f) { | |
00e64b67 | 1232 | stop(kx); |
35c8b547 MW |
1233 | if (f & 1) a_warn("KX", "?PEER", kx->p, "private-key-expired", A_END); |
1234 | if (f & 2) a_warn("KX", "?PEER", kx->p, "public-key-expired", A_END); | |
00e64b67 | 1235 | kx->f &= ~KXF_PUBKEY; |
1236 | return (-1); | |
1237 | } | |
1238 | return (0); | |
1239 | } | |
1240 | ||
0617b6e7 | 1241 | /* --- @kx_start@ --- * |
410c8acf | 1242 | * |
1243 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
de014da6 | 1244 | * @int forcep@ = nonzero to ignore the quiet timer |
410c8acf | 1245 | * |
1246 | * Returns: --- | |
1247 | * | |
0617b6e7 | 1248 | * Use: Stimulates a key exchange. If a key exchage is in progress, |
1249 | * a new challenge is sent (unless the quiet timer forbids | |
1250 | * this); if no exchange is in progress, one is commenced. | |
410c8acf | 1251 | */ |
1252 | ||
de014da6 | 1253 | void kx_start(keyexch *kx, int forcep) |
410c8acf | 1254 | { |
1255 | time_t now = time(0); | |
410c8acf | 1256 | |
00e64b67 | 1257 | if (checkpub(kx)) |
1258 | return; | |
de014da6 | 1259 | if (forcep || !VALIDP(kx, now)) { |
0617b6e7 | 1260 | stop(kx); |
1261 | start(kx, now); | |
f43df819 | 1262 | a_notify("KXSTART", "?PEER", kx->p, A_END); |
410c8acf | 1263 | } |
0617b6e7 | 1264 | resend(kx); |
1265 | } | |
1266 | ||
1267 | /* --- @kx_message@ --- * | |
1268 | * | |
1269 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1270 | * @unsigned msg@ = the message code | |
1271 | * @buf *b@ = pointer to buffer containing the packet | |
1272 | * | |
1273 | * Returns: --- | |
1274 | * | |
1275 | * Use: Reads a packet containing key exchange messages and handles | |
1276 | * it. | |
1277 | */ | |
1278 | ||
1279 | void kx_message(keyexch *kx, unsigned msg, buf *b) | |
1280 | { | |
ff143952 | 1281 | struct timeval now, tv; |
0617b6e7 | 1282 | stats *st = p_stats(kx->p); |
1283 | size_t sz = BSZ(b); | |
1284 | int rc; | |
1285 | ||
ff143952 | 1286 | gettimeofday(&now, 0); |
a06d57a3 | 1287 | rs_reset(&kx->rs); |
010e6f63 | 1288 | if (kx->f & KXF_CORK) { |
ff143952 | 1289 | start(kx, now.tv_sec); |
a06d57a3 | 1290 | rs_time(&kx->rs, &tv, &now); |
ff143952 | 1291 | settimer(kx, &tv); |
b41feb10 | 1292 | a_notify("KXSTART", "?PEER", kx->p, A_END); |
010e6f63 MW |
1293 | } |
1294 | ||
00e64b67 | 1295 | if (checkpub(kx)) |
1296 | return; | |
1297 | ||
ff143952 | 1298 | if (!VALIDP(kx, now.tv_sec)) { |
0617b6e7 | 1299 | stop(kx); |
ff143952 | 1300 | start(kx, now.tv_sec); |
410c8acf | 1301 | } |
0617b6e7 | 1302 | T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'", |
1303 | msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); ) | |
1304 | ||
1305 | switch (msg) { | |
1306 | case KX_PRECHAL: | |
de7bd20b MW |
1307 | rc = doprechallenge(kx, b); |
1308 | break; | |
0617b6e7 | 1309 | case KX_CHAL: |
de7bd20b | 1310 | rc = dochallenge(kx, b); |
0617b6e7 | 1311 | break; |
1312 | case KX_REPLY: | |
1313 | rc = doreply(kx, b); | |
1314 | break; | |
1315 | case KX_SWITCH: | |
1316 | rc = doswitch(kx, b); | |
1317 | break; | |
1318 | case KX_SWITCHOK: | |
1319 | rc = doswitchok(kx, b); | |
1320 | break; | |
1321 | default: | |
f43df819 | 1322 | a_warn("KX", "?PEER", kx->p, "unknown-message", "0x%02x", msg, A_END); |
0617b6e7 | 1323 | rc = -1; |
1324 | break; | |
410c8acf | 1325 | } |
410c8acf | 1326 | |
0617b6e7 | 1327 | if (rc) |
1328 | st->n_reject++; | |
1329 | else { | |
1330 | st->n_kxin++; | |
1331 | st->sz_kxin += sz; | |
1332 | } | |
410c8acf | 1333 | } |
1334 | ||
1335 | /* --- @kx_free@ --- * | |
1336 | * | |
1337 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1338 | * | |
1339 | * Returns: --- | |
1340 | * | |
1341 | * Use: Frees everything in a key exchange context. | |
1342 | */ | |
1343 | ||
1344 | void kx_free(keyexch *kx) | |
1345 | { | |
0617b6e7 | 1346 | stop(kx); |
35c8b547 MW |
1347 | km_unref(kx->kpub); |
1348 | km_unref(kx->kpriv); | |
410c8acf | 1349 | } |
1350 | ||
1351 | /* --- @kx_newkeys@ --- * | |
1352 | * | |
1353 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1354 | * | |
1355 | * Returns: --- | |
1356 | * | |
1357 | * Use: Informs the key exchange module that its keys may have | |
1358 | * changed. If fetching the new keys fails, the peer will be | |
1359 | * destroyed, we log messages and struggle along with the old | |
1360 | * keys. | |
1361 | */ | |
1362 | ||
1363 | void kx_newkeys(keyexch *kx) | |
1364 | { | |
35c8b547 MW |
1365 | kdata *kpriv, *kpub; |
1366 | unsigned i; | |
1367 | int switchp; | |
1368 | time_t now = time(0); | |
1369 | ||
1370 | T( trace(T_KEYEXCH, "keyexch: checking new keys for `%s'", | |
1371 | p_name(kx->p)); ) | |
1372 | ||
1373 | /* --- Find out whether we can use new keys --- * | |
1374 | * | |
1375 | * Try each available combination of new and old, public and private, | |
1376 | * except both old (which is status quo anyway). The selection is encoded | |
1377 | * in @i@, with bit 0 for the private key and bit 1 for public key; a set | |
1378 | * bit means to use the old value, and a clear bit means to use the new | |
1379 | * one. | |
1380 | * | |
1381 | * This means that we currently prefer `old private and new public' over | |
1382 | * `new private and old public'. I'm not sure which way round this should | |
1383 | * actually be. | |
1384 | */ | |
1385 | ||
1386 | for (i = 0; i < 3; i++) { | |
1387 | ||
1388 | /* --- Select the keys we're going to examine --- * | |
1389 | * | |
1390 | * If we're meant to have a new key and don't, then skip this | |
1391 | * combination. | |
1392 | */ | |
1393 | ||
1394 | T( trace(T_KEYEXCH, "keyexch: checking %s private, %s public", | |
1395 | i & 1 ? "old" : "new", i & 2 ? "old" : "new"); ) | |
1396 | ||
1397 | if (i & 1) kpriv = kx->kpriv; | |
1398 | else if (kx->kpriv->kn->kd != kx->kpriv) kpriv = kx->kpriv->kn->kd; | |
1399 | else { | |
1400 | T( trace(T_KEYEXCH, "keyexch: private key unchanged, skipping"); ) | |
1401 | continue; | |
1402 | } | |
1403 | ||
1404 | if (i & 2) kpub = kx->kpub; | |
1405 | else if (kx->kpub->kn->kd != kx->kpub) kpub = kx->kpub->kn->kd; | |
1406 | else { | |
1407 | T( trace(T_KEYEXCH, "keyexch: public key unchanged, skipping"); ) | |
1408 | continue; | |
1409 | } | |
1410 | ||
1411 | /* --- Skip if either key is expired --- * | |
1412 | * | |
1413 | * We're not going to get far with expired keys, and this simplifies the | |
1414 | * logic below. | |
1415 | */ | |
1416 | ||
1417 | if (KEY_EXPIRED(now, kx->kpriv->t_exp) || | |
1418 | KEY_EXPIRED(now, kx->kpub->t_exp)) { | |
1419 | T( trace(T_KEYEXCH, "keyexch: %s expired, skipping", | |
1420 | !KEY_EXPIRED(now, kx->kpriv->t_exp) ? "public key" : | |
1421 | !KEY_EXPIRED(now, kx->kpub->t_exp) ? "private key" : | |
1422 | "both keys"); ) | |
1423 | continue; | |
1424 | } | |
1425 | ||
1426 | /* --- If the groups don't match then we can't use this pair --- */ | |
1427 | ||
1428 | if (!km_samealgsp(kpriv, kpub)) { | |
1429 | T( trace(T_KEYEXCH, "keyexch: peer `%s' group mismatch; " | |
1430 | "%s priv `%s' and %s pub `%s'", p_name(kx->p), | |
1431 | i & 1 ? "old" : "new", km_tag(kx->kpriv), | |
1432 | i & 2 ? "old" : "new", km_tag(kx->kpub)); ) | |
1433 | continue; | |
1434 | } | |
1435 | goto newkeys; | |
1436 | } | |
1437 | T( trace(T_KEYEXCH, "keyexch: peer `%s' continuing with old keys", | |
1438 | p_name(kx->p)); ) | |
1439 | return; | |
1440 | ||
1441 | /* --- We've chosen new keys --- * | |
1442 | * | |
1443 | * Switch the new ones into place. Neither of the keys we're switching to | |
1444 | * is expired (we checked that above), so we should just crank everything | |
1445 | * up. | |
1446 | * | |
1447 | * A complication arises: we don't really want to force a new key exchange | |
1448 | * unless we have to. If the group is unchanged, and we're currently | |
1449 | * running OK, then we should just let things lie. | |
1450 | */ | |
1451 | ||
1452 | newkeys: | |
1453 | switchp = ((kx->f & KXF_DEAD) || | |
1454 | kx->s != KXS_SWITCH || | |
5b9f3d37 MW |
1455 | kpriv->grp->ops != kx->kpriv->grp->ops || |
1456 | !kpriv->grp->ops->samegrpp(kpriv->grp, kx->kpriv->grp)); | |
35c8b547 MW |
1457 | |
1458 | T( trace(T_KEYEXCH, "keyexch: peer `%s' adopting " | |
1459 | "%s priv `%s' and %s pub `%s'; %sforcing exchange", p_name(kx->p), | |
1460 | i & 1 ? "old" : "new", km_tag(kx->kpriv), | |
1461 | i & 2 ? "old" : "new", km_tag(kx->kpub), | |
1462 | switchp ? "" : "not "); ) | |
1463 | ||
1464 | if (switchp) stop(kx); | |
1465 | km_ref(kpriv); km_unref(kx->kpriv); kx->kpriv = kpriv; | |
1466 | km_ref(kpub); km_unref(kx->kpub); kx->kpub = kpub; | |
00e64b67 | 1467 | kx->f |= KXF_PUBKEY; |
35c8b547 | 1468 | if (switchp) { |
410c8acf | 1469 | T( trace(T_KEYEXCH, "keyexch: restarting key negotiation with `%s'", |
1470 | p_name(kx->p)); ) | |
00e64b67 | 1471 | start(kx, time(0)); |
1472 | resend(kx); | |
410c8acf | 1473 | } |
1474 | } | |
1475 | ||
1476 | /* --- @kx_init@ --- * | |
1477 | * | |
1478 | * Arguments: @keyexch *kx@ = pointer to key exchange context | |
1479 | * @peer *p@ = pointer to peer context | |
1480 | * @keyset **ks@ = pointer to keyset list | |
010e6f63 | 1481 | * @unsigned f@ = various useful flags |
410c8acf | 1482 | * |
1483 | * Returns: Zero if OK, nonzero if it failed. | |
1484 | * | |
1485 | * Use: Initializes a key exchange module. The module currently | |
1486 | * contains no keys, and will attempt to initiate a key | |
1487 | * exchange. | |
1488 | */ | |
1489 | ||
010e6f63 | 1490 | int kx_init(keyexch *kx, peer *p, keyset **ks, unsigned f) |
410c8acf | 1491 | { |
fe2a5dcf | 1492 | if ((kx->kpriv = km_findpriv(p_privtag(p))) == 0) goto fail_0; |
35c8b547 | 1493 | if ((kx->kpub = km_findpub(p_tag(p))) == 0) goto fail_1; |
0d9974ba | 1494 | if (!km_samealgsp(kx->kpriv, kx->kpub)) { |
cc3e30a4 | 1495 | a_warn("KX", "?PEER", p, "group-mismatch", |
fe2a5dcf | 1496 | "local-private-key", "%s", p_privtag(p), |
35c8b547 MW |
1497 | "peer-public-key", "%s", p_tag(p), |
1498 | A_END); | |
1499 | goto fail_2; | |
1500 | } | |
1501 | ||
410c8acf | 1502 | kx->ks = ks; |
1503 | kx->p = p; | |
010e6f63 | 1504 | kx->f = KXF_DEAD | KXF_PUBKEY | f; |
a06d57a3 | 1505 | rs_reset(&kx->rs); |
010e6f63 MW |
1506 | if (!(kx->f & KXF_CORK)) { |
1507 | start(kx, time(0)); | |
1508 | resend(kx); | |
1509 | /* Don't notify here: the ADD message hasn't gone out yet. */ | |
1510 | } | |
410c8acf | 1511 | return (0); |
35c8b547 MW |
1512 | |
1513 | fail_2: | |
1514 | km_unref(kx->kpub); | |
1515 | fail_1: | |
1516 | km_unref(kx->kpriv); | |
1517 | fail_0: | |
1518 | return (-1); | |
410c8acf | 1519 | } |
1520 | ||
1521 | /*----- That's all, folks -------------------------------------------------*/ |